Many consumer level video sources, such as DVDs and digital cable/satellite carriers provide 4:2:0 chroma video to a video display appliance. Subsequently, the video appliance converts the 4:2:0 chroma video into 4:2:2 chroma video, such that it may be displayed using an interlaced display. Additionally, the 4:2:2 chroma video may be deinterlaced to provide progressive video at twice the original 4:2:0 chroma frame rate.
When a typical 4:2:0 chroma frame is converted to 4:2:2 chroma frames, two 4:2:0 chroma fields are generated. The two 4:2:0 chroma fields comprise a top 4:2:0 chroma field and a bottom 4:2:0 chroma field. Subsequently, two corresponding top and bottom 4:2:2 chroma fields may be generated by vertically interpolating their respective top and bottom 4:2:0 chroma fields. Thereafter, the top and bottom 4:2:2 chroma fields are transmitted to a deinterlacer. The deinterlacer may deinterlace the 4:2:2 chroma fields in one of two ways. The deinterlacer may “weave” chroma samples from adjacent fields to produce progressive video at double the previous frame rate, or it may “bob” (vertically interpolate) chroma from the pixels provided from each respective field. Unfortunately, either option causes undesirable artifacts.
When a deinterlacer performs a “weave”, 4:2:2 chroma sample points that are spatially close to 4:2:0 sample points generate colors that are similar. However, the 4:2:2 chroma sample points that are distant from a given 4:2:0 point are heavily interpolated between the two nearest available 4:2:0 chroma sample points, resulting in degradation of picture quality. When there is a sharp transition of color, from red to green, for example, these heavily interpolated points appear a brownish color. If the deinterlacer weaves chroma from adjacent fields to create absent pixel chroma, one may observe a “hanging chroma line” of brown in the region that should be green, and another “hanging chroma line” of brown in the region that should be red, for example.
Alternatively, when a deinterlacer performs a “bob”, the output frame originating from the top field will transition vertically from green to red sooner compared to the bottom field originated output frame; however, the bottom field originated output frame remains green vertically much longer until finally transitioning to red. In this instance, the differences that occur between top and bottom output frames result in undesirable flickering.
The limitations and disadvantages of conventional and traditional approaches will become apparent to one of skill in the art, through comparison of such systems with some aspects of the present invention as set forth in the remainder of the present application with reference to the drawings.